I think part of the reason those products have been left off is that they're not easily substitutable. That's my guess. Food packaging, for example, is a tricky one.
Right now, from what we know about the toxicity of plastics and from the risk assessments in place, the risk has to do with the size and quantity of the microplastics in the gut of an organism. There is some evidence, though, that certain plastic types can be more toxic than others. For example, you mentioned polystyrene and PVC. Tire dust is another example. In the case of tire dust, we understand that it might be more hazardous than a polyethylene. As for PVC and polystyrene, while there are chemicals in them that can make them more toxic than other types of plastics, I don't think there's enough evidence yet to suggest that they're leaching at a rate that could harm organisms.
Right now, it's microplastics in general, as a mixture, that should be kept out of the environment, regardless of material type.